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Title: Observation of 9-Fold Coordinated Amorphous TiO2 at High Pressure

Abstract

Knowledge of the structure in amorphous dioxides is important in many fields of science and engineering. In this paper, we report new experimental results of high-pressure polyamorphism in amorphous TiO2 (a-TiO2). Our data show that the Ti coordination number (CN) increases from 7.2 ± 0.3 at ~16 GPa to 8.8 ± 0.3 at ~70 GPa and finally reaches a plateau at 8.9 ± 0.3 at ≲86 GPa. The evolution of the structural changes under pressure is rationalized by the ratio ($γ$) of the ionic radius of Ti to that of O. It appears that the CN ≈ 9 plateau correlates with the two 9-fold coordinated polymorphs (cotunnite, Fe2P) with different $γ$ values. This CN-$γ$ relationship is compared with those of a-SiO2 and a-GeO2, displaying remarkably consistent behavior between CN and $γ$. The unified CN-$γ$ relationship may be generally used to predict the compression behavior of amorphous AO2 compounds under extreme conditions.

Authors:
ORCiD logo [1];  [2];  [2]; ORCiD logo [3];  [1]; ORCiD logo [1];  [1];  [4]; ORCiD logo [1]
  1. Argonne National Lab. (ANL), Argonne, IL (United States). High Pressure Collaborative Access Team
  2. Carnegie Inst. of Washington, Argonne, IL (United States)
  3. Jilin Univ., Changchun (China). State Key Lab. of Superhard Materials
  4. Univ. of Chicago, IL (United States). Center for Advanced Radiation Sources (CARS)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1607480
Grant/Contract Number:  
AC02-06CH11357; EAR-1722495; FG02-99ER45775; EAR-1620548
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry Letters
Additional Journal Information:
Journal Volume: 11; Journal Issue: 2; Journal ID: ISSN 1948-7185
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Crystal structure; Chemical structure; Compression; Physical and chemical processes; Amorphous materials

Citation Formats

Shu, Yu, Kono, Yoshio, Ohira, Itaru, Li, Quanjun, Hrubiak, Rostislav, Park, Changyong, Kenney-Benson, Curtis, Wang, Yanbin, and Shen, Guoyin. Observation of 9-Fold Coordinated Amorphous TiO2 at High Pressure. United States: N. p., 2019. Web. https://doi.org/10.1021/acs.jpclett.9b03378.
Shu, Yu, Kono, Yoshio, Ohira, Itaru, Li, Quanjun, Hrubiak, Rostislav, Park, Changyong, Kenney-Benson, Curtis, Wang, Yanbin, & Shen, Guoyin. Observation of 9-Fold Coordinated Amorphous TiO2 at High Pressure. United States. https://doi.org/10.1021/acs.jpclett.9b03378
Shu, Yu, Kono, Yoshio, Ohira, Itaru, Li, Quanjun, Hrubiak, Rostislav, Park, Changyong, Kenney-Benson, Curtis, Wang, Yanbin, and Shen, Guoyin. Mon . "Observation of 9-Fold Coordinated Amorphous TiO2 at High Pressure". United States. https://doi.org/10.1021/acs.jpclett.9b03378. https://www.osti.gov/servlets/purl/1607480.
@article{osti_1607480,
title = {Observation of 9-Fold Coordinated Amorphous TiO2 at High Pressure},
author = {Shu, Yu and Kono, Yoshio and Ohira, Itaru and Li, Quanjun and Hrubiak, Rostislav and Park, Changyong and Kenney-Benson, Curtis and Wang, Yanbin and Shen, Guoyin},
abstractNote = {Knowledge of the structure in amorphous dioxides is important in many fields of science and engineering. In this paper, we report new experimental results of high-pressure polyamorphism in amorphous TiO2 (a-TiO2). Our data show that the Ti coordination number (CN) increases from 7.2 ± 0.3 at ~16 GPa to 8.8 ± 0.3 at ~70 GPa and finally reaches a plateau at 8.9 ± 0.3 at ≲86 GPa. The evolution of the structural changes under pressure is rationalized by the ratio ($γ$) of the ionic radius of Ti to that of O. It appears that the CN ≈ 9 plateau correlates with the two 9-fold coordinated polymorphs (cotunnite, Fe2P) with different $γ$ values. This CN-$γ$ relationship is compared with those of a-SiO2 and a-GeO2, displaying remarkably consistent behavior between CN and $γ$. The unified CN-$γ$ relationship may be generally used to predict the compression behavior of amorphous AO2 compounds under extreme conditions.},
doi = {10.1021/acs.jpclett.9b03378},
journal = {Journal of Physical Chemistry Letters},
number = 2,
volume = 11,
place = {United States},
year = {2019},
month = {12}
}

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